1. Field of the Invention
This invention relates generally to methods and devices for performing surgery, and more particularly, to methods and devices for performing minimally invasive surgery, such as cardiac surgery, including, but not limited to, coronary artery bypass grafting, valvular, dysrhythmia and aortic surgery, as well as thoracic surgical procedures.
2. Discussion of Related Art
Coronary artery disease is the largest or one of the largest causes of death in the United States. Interventions for coronary artery disease include education, medication, percutaneous coronary intervention, such as balloon angioplasty and stenting, and coronary bypass surgery.
Coronary artery bypass surgery is the most common type of heart surgery, with over 300,000 people having successful surgery in the United States each year. As is well known, arteries can become clogged over time by the build-up of fatty plaque in the artery wall. Coronary bypass surgery bypasses the diseased artery with a new blood vessel taken from the leg (greater saphenous vein) or an artery from the chest or arm. This procedure creates a new route for blood to flow.
Coronary artery bypass surgery is typically performed through an open chest exposure (i.e., to access and circumvent obstructed coronary arteries). A common approach involves making a 15-20 cm long incision in the skin overlying the breastbone, and splitting and separating the sternum to provide full access to the heart. With reference to FIG. 1, during coronary artery bypass surgery, the patient's breastbone 10 (sternum) is divided by means of a sternal saw. As stated above, a typical incision 12 is approximately 15-20 cm long. After appropriate bypass conduits are taken (e.g., a vein from the patient's leg), a sternal retractor is placed to spread the skin and breastbone to expose the heart and vessels for the bypass procedure. During the procedure, the heart may be stopped, and the patient's blood is sent through a heart-lung machine. This procedure typically takes three to five hours to perform, depending on the number of bypasses required. Three to four smaller incisions may be made inferior to the initial incision for drain placement around the heart after the procedure is completed. At the end of the procedure, the patient's breastbone is wired back together and the muscle and skin are closed as well with absorbable sutures.
The long incision 12 described above, which starts from the very top of the breastbone and extends the bottom of the breastbone, cuts not only the breastbone, but tissue and muscle as well. During the operation, a sternal retractor is situated above the cavity to spread the skin, tissue, muscle and breastbone. This large incision may cause several potential negative side effects. Of all the layers of body tissue, the skin is the most innervated with sensory nerves, as compared to muscle and breastbone. Further, closure of the pectoral muscles must be done in a fashion that results in much more tension on the muscles than the native state. This may result in extreme pain at rest which is exacerbated by any action that stretches the skin or muscle, which can lead to respiratory complications and general inactivity due to splinting. There may also be associated negative psychological effects.
Experience from other surgical procedures has shown that minimized surgical incisions result in shorter intensive care unit and hospital stays, less complications, less pain, and an overall better experience for the patient. For example, prior techniques in gallbladder removal (cholecystectomy) involved a substantial incision of 12-15 cm in the abdomen, which results in expected increased patient discomfort. When laparoscopic cholecystectomy was developed, which involves making four small incisions (each between 0.5 and 1.2 cm long) and the use of video equipment, the results was shorter hospital stays, less complications and quicker patient recovery.
Pecutaneous coronary intervention (“PCI”) was developed as a less invasive way than coronary artery bypass grafting to treat coronary artery disease. PCI has progressed from balloon angioplasty, to stents, to drug eluting stents. However, PCI may not be suitable for patients who are diabetic or who have three or more artery blockages, according to the official recommendations of the American College of Cardiology.
Although there are examples of “minimal” invasive coronary artery bypass surgery, such surgery typically involves bypassing only left sided, anterior coronary vessels, through a limited rib spreading incision. This operation is only used for patients whose entire set of blockages can be bypassed through this smaller incision which represents a minority of patients.
Minimally invasive approaches to all types of operations are desirable because of the advantages of less scarring and pain, shorter hospital stays and recovery time. With minimally invasive approaches, such approaches generally try to avoid splitting the sternum and may use a series of incisions to gain adequate visualization and access the patient's heart. Rarely, with these approaches, is it possible to use videoscopic imaging systems or robotic guidance devices. While these techniques may provide advantages when dealing with a limited set of anatomic heart problems, they are not widely adopted due to their cumbersome nature, and the limited mobility through relatively fixed bony and muscular structures. There is concern that sub-par results may be obtained. In addition with small incisions, reduced three-dimensional visibility and perceptual orientation may increase some risk to the patient.